JPH0661000A - Circular accelerator and circular accelerator operating method and semiconductor exposure device - Google Patents

Abstract

PURPOSE:To provide a small circular accelerator and a circular accelerator operating method capable of generating highly bright emission light and a semiconductor exposure device capable of using the highly bright emission light. CONSTITUTION:An electron beam 12 emitted from a front stage accelerator 11 is made incident in an accumulation ring by means of an incident unit 13, and is accelerated, and is accumulated. Afterwards, an inserted light source 18 arranged in a straight line orbit part between a main deflection magnet 14 and an auxiliary deflection magnet 15 is excited, and an alternating magnetic field is generated inside of it. The electron beam meanders or is put in spiral motion by means of this alternating magnetic field, and beams of emission light emitted from the apex of an meandering orbit or a spiral orbit are superposed upon each other, so that highly bright emission light 19 can be generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron or positron circular accelerator, and more particularly to a circular accelerator suitable for producing synchrotron radiation having a small size and high brightness, and a method of operating the same.

[0002]

2. Description of the Related Art Regarding the conventional circular accelerator, a technical magazine, monthly physics Vol.5 No.11, 1984, p.711.
The synchrotron radiation light generating device described in p. A conventional example will be described with reference to the schematic view of the synchrotron radiation generator shown in FIG. An electron or positron beam (hereinafter referred to as an electron beam) emitted from the pre-stage accelerator 21 is made incident on the storage ring by the injector system 22. The incident electron beam or the like is converged or diverged by a quadrupole magnet 26,
It is held on the orbit 28 by the orbit correction steering magnet 27 and the deflection magnet 23. After that, in the case of a storage ring that has an electron beam acceleration function, the high-frequency acceleration cavity
5 accelerates in the storage ring to the desired energy. When the incident energy is the desired energy, the energy is stored as it is. When the electron beam or the like accumulated with desired energy circulates in the accumulation ring, a part of the energy is emitted as radiant light 24 every time it is deflected by the deflection magnet 23. This emitted light is used for fine processing of semiconductors. The energy lost due to the emission of this synchrotron radiation is applied to the high-frequency acceleration cavity 25 provided in the storage ring.
By compensating with, the electron beam or the like of desired energy can be held on the orbit 28 in the storage ring. As a method of increasing the luminance in the long wavelength region of the radiated light 24 emitted from the deflection magnet 23, an alternating magnetic field is applied along the circular orbit 28 in the storage ring to cause the electron beam or the like to meander or spiral. Accordingly, an insertion type light emitting device (hereinafter referred to as an insertion light source) 18 that superposes radiated light emitted from the apex of a meandering orbit or a spiral orbit is used.

[0003]

However, since it is necessary to install the insertion light source on the linear orbital portion of the electron beam or the like, there is a problem that a large number of insertion light sources cannot be installed in the storage ring that requires miniaturization. is there. That is, the small storage ring has a small number of linear orbits, and as described above, the 4-pole magnet, the steering magnet, the injector system, and the high-frequency accelerating cavity are installed in the linear orbital portion. It is not possible to increase the brightness by installing an insertion light source.

An object of the present invention is to provide a circular accelerator which is small in size and can generate radiant light with high brightness, and a method of operating the circular accelerator,
Another object of the present invention is to provide a semiconductor exposure apparatus that can utilize radiant light with high brightness.

[0005]

A first aspect of the present invention for achieving the above object is to provide means for superimposing radiated light on a deflector for deflecting an electron beam or a positron beam.

A second invention for achieving the above object is as follows:
A plurality of deflecting magnets are provided in a deflecting unit that deflects an electron beam or a positron beam, the deflecting magnets have a set of adjacent deflecting magnets having different excitation amounts, and an insertion light source is provided between the deflecting magnets. is there.

According to a third aspect of the invention, a plurality of deflecting magnets are provided in a deflecting section for deflecting an electron beam or a positron beam, and the deflecting magnets have a set of adjacent deflecting magnets having different deflection radii. An insertion light source is provided between them.

According to a fourth aspect of the invention, a plurality of deflecting magnets are provided in a deflecting unit for deflecting an electron beam or a positron beam, and the deflecting magnets have a set of adjacent deflecting magnets having different deflection angles. An insertion light source is provided between them.

According to a fifth aspect of the invention, a plurality of deflecting magnets are provided in a deflecting unit for deflecting an electron beam or a positron beam, and the deflecting magnets are adjacent to each other with a set of adjacent deflecting magnets having different exciting amounts. A pair of deflection magnets, and an insertion light source is provided between the deflection magnets having the same excitation amount.

According to a sixth aspect of the present invention, among the radiated light emitted from the deflecting section for deflecting the electron beam or the positron beam, the radiated light in a wavelength range longer than the peak wavelength at which the brightness is maximized is utilized. Is.

In a seventh aspect of the present invention, the insertion light source is operated when an electron beam or a positron beam is incident to shorten the radiation decay time of the betatron oscillation of the beam.

According to an eighth aspect of the invention, a plurality of deflecting magnets are provided in a deflecting section for deflecting an electron beam or a positron beam, and the deflecting magnets have a set of adjacent deflecting magnets having different excitation amounts. A circular accelerator provided with an insertion light source therebetween, a means for reflecting or condensing the radiation light emitted from the deflection section, and a desired pattern on the semiconductor substrate using the radiation light reflected or focused by the means And a pattern transfer device for transferring

[0013]

According to the first aspect of the present invention, by providing the deflecting section with means for superposing the emitted light, the emitted light emitted from the electron beam or the like in the deflecting section can be superposed.
It is possible to generate radiant light with high brightness.

In the second invention and the fifth invention, if the deflection unit is provided with a plurality of deflection magnets each having a set of adjacent deflection magnets having different excitation amounts, the excitation amount of the deflection magnets is appropriately selected. A straight track portion can be provided between the deflecting magnets with almost no change in the track length of the deflecting portion. By providing the insertion light source in the linear orbital portion between the deflection magnets, it is possible to cause the electron beam or the like to meander or spiral in the insertion light source, and superpose the emitted light from the apex of the serpentine orbit or the spiral orbit. Therefore, it is possible to generate radiant light with high brightness without changing the size of the small storage ring.

According to the third aspect of the invention, by providing a plurality of deflection magnets each having a set of adjacent deflection magnets having different deflection radii in the deflection section, if the deflection radius of the deflection magnet is appropriately selected, the trajectory length of the deflection section. It is possible to provide a linear track portion between the deflection magnets with almost no change. Therefore, by providing the insertion light source in the straight track portion between the deflection magnets, it is possible to generate radiant light with high brightness without changing the size of the small storage ring.

According to the fourth aspect of the present invention, by providing a plurality of deflecting magnets each having a pair of adjacent deflecting magnets having different deflecting angles in the deflecting section, if the deflecting angle of the deflecting magnet is appropriately selected, the orbit length of the deflecting section is increased. It is possible to provide a linear track portion between the deflection magnets with almost no change. Therefore, by providing the insertion light source in the straight track portion between the deflection magnets, it is possible to generate radiant light with high brightness without changing the size of the small storage ring.

According to the sixth aspect of the invention, of the radiated light emitted from the deflection section, the radiated light in the wavelength range longer than the peak wavelength at which the brightness is maximized is used, so that the reflecting means such as a mirror can be appropriately selected. For example, since the emitted light can be reflected and collected over a wide range of reflection angles, the emitted light can have high brightness.

In the seventh invention, the insertion light source is operated at the time of incidence of an electron beam or the like to shorten the radiative decay time of the betatron oscillation of the beam so that a low energy electron beam or the like is made to enter the storage ring many times. it can. Therefore,
It is possible to increase the stored current in the storage ring and to generate a bright emission light.

According to the eighth aspect of the present invention, by providing a plurality of deflection magnets having a pair of adjacent deflection magnets having different excitation amounts in the deflection section, if the excitation amount of the deflection magnet is appropriately selected, the orbit length of the deflection section. It is possible to provide a straight track portion between the deflection magnets with almost no change. Therefore, by providing an insertion light source in the linear orbital portion between the deflection magnets, radiant light with high brightness can be generated without changing the size of the small storage ring. By using this radiant light, a semiconductor with high brightness can be obtained. An exposure process can be performed.

[0020]

EXAMPLE A first example of the present invention will be described with reference to FIG. FIG. 1 shows a schematic diagram of a racetrack type synchrotron radiation light generator using an electron beam. This figure shows
It comprises a storage ring for accelerating and storing the electron beam, and a pre-stage accelerator 11 for injecting the electron beam 12 into the storage ring. The storage ring includes an injector 13 for the electron beam 12, a quadrupole magnet 16 for converging or diverging, a high frequency acceleration cavity 17 for supplying energy, and a deflecting unit for deflection. The deflecting unit is composed of a main deflecting magnet 14 and an auxiliary deflecting magnet 15, and the main deflecting magnet 14 and the auxiliary deflecting magnet 1 are made to have an excitation amount larger than that of the auxiliary deflecting magnet 15.
Four insertion light sources 18 are arranged on the linear orbit portion formed between the five. Electron beam 12 emitted from pre-accelerator 11
After being injected into the storage ring by the injector 13, the main deflection magnet 14, the auxiliary deflection magnet 15, the quadrupole magnet 16 and the high frequency acceleration cavity 17 are pattern-operated to synchronize the electron beam to a desired energy. Tron accelerates and accumulates in the accumulation ring. After accumulating the electron beam, the insertion light source 18 installed on the linear orbit between the main deflection magnet 14 and the auxiliary deflection magnet 15 is excited to generate an alternating magnetic field in the insertion light source. This alternating magnetic field causes the electron beam to meander or spiral, and superimposes the radiated light emitted from the apex of the meandering orbit or the spiral orbit, thereby making it possible to generate radiant light 19 with high brightness. It is also possible to superimpose the emitted light by using a permanent magnet as the insertion light source and narrowing the magnetic pole width.

Here, the increase in brightness when the configuration of FIG. 1 is used will be described. Consider a case where a racetrack microtron is used as the pre-stage accelerator 11, electrons are accelerated to about 20 MeV and incident, and then accelerated to 1 GeV in the storage ring to be accumulated. At this time, the magnetic field B of the deflection magnet is: B = E / (0.3ρ) (Equation 1) B: Deflection magnetic field (T) E: Electron energy (GeV) ρ: Radius of curvature of deflection magnet (m) Become. The peak wavelength λ of the emitted light emitted from the insertion light source 18 is λ = λ ₀ (1 + cK ² ) / 2γ ² (Equation 2) λ: The peak wavelength (m) λ of the emission light emitted from the insertion light source ₀ : Inserted light source pitch (m) c: Constant determined by the type of inserted light source c = 1/2 Planar type c = 1 Helical type K: Constant characterizing the inserted light source K = 93.4Bλ ₀ γ: Gamma of relativity (= Electron beam energy / electron rest energy). There are an undulator and a wiggler as an insertion light source. An undulator having a large number of vibrations of an electron beam in the insertion light source is called an undulator and a one having a small number of vibrations is called a wiggler. Constant K shown in equation 2
, The undulator with K ≦ 1 is 1 << K
What is is a wiggler. Due to the difference in the frequency of vibration between the undulator and the wiggler, there is a difference in the effect of increasing the brightness. That is, the undulator can selectively increase the brightness of a specific wavelength, as indicated by 33 in FIG. This is because the number of vibrations in the undulator is large, so that the superposition of the emitted light is sufficient,
This is because the wavelengths are aligned. On the other hand, the wiggler does not have wavelength selectivity like an undulator, as indicated by reference numeral 32 in FIG. 3, and the luminance becomes high over a wide wavelength range. In particular, it is characterized in that the brightness on the short wavelength side can be increased as compared with the spectrum 31 of the deflection magnet. This is because the number of vibrations in the wiggler is small, so that the radiated lights are not sufficiently superposed.

A helical undulator will be described below as an example. The radiance P of the radiated light when the helical undulator is used is P = 6.5 × 10 ¹¹ E ² N ² (Equation 3) P: Luminance when the insertion light source is used N: The number of cycles of the insertion light source Can be represented. The brightness P ′ of the radiated light when the insertion light source is not used is P ′ = 2 × 10 ¹¹ E ² (Equation 4). Therefore, when the insertion light source is used, the conventional brightness is set to the cycle number of the insertion light source. It can be increased in proportion to the square.

Next, the miniaturization will be described. The wavelength of synchrotron radiation is set to about 150Å as an example. The energy of electrons is set to E in order to reduce the brightness of synchrotron radiation as much as possible.
FIG. 2 and FIG. 1 show the conventional device and the present invention with = 1 GeV constant.
To compare.

First, the size of the conventional device is estimated. The peak wavelength λ'of the radiation emitted from the deflection magnet in the conventional device
Is given by: λ '= 18.6 / (E ² B) (Equation 5) λ': Peak wavelength (Å) of radiation emitted from the deflection magnet. The magnetic field of the deflection magnet required to set the peak wavelength to λ ′ = 150Å is B = 0.12 T from the equation (5). The radius of curvature of the deflection magnet corresponding to this is given by
When ρ = 27.8 m, a storage ring as shown in FIG. 2 is constructed by using this deflecting magnet, and the circumference of the storage ring becomes extremely large, at least about 170 m. Therefore, it is considered to prioritize downsizing even if a slight decrease in brightness is recognized and to use radiated light in a wavelength range longer than the peak wavelength. In order to downsize the storage ring, it is necessary to reduce the radius of curvature ρ of the deflection magnet. In order to make the radius of curvature ρ smaller than the expression 1, it is necessary to increase the deflection magnetic field B, and accordingly, the peak wavelength λ ′ of the emitted light expressed by the expression 5 becomes smaller. Assuming now that the peak wavelength is λ ′ = 10Å,
From the spectral characteristics of the synchrotron radiation shown in 31
The brightness at 0Å is 1 / the brightness P'at the peak wavelength.
It falls to about 3 to 1/2. If you notice this decrease in brightness,
From Equation 5, the deflection magnetic field is B = 1.9T, and from this and Equation 1, the radius of curvature is ρ = 1.8 m. As a result, the circumference of the storage ring including the straight track portion can be reduced to about 17 m.

On the other hand, in the case of the present invention shown in FIG. 1, the insertion light source for realizing the peak wavelength λ = 150Å of the emitted light is
For example, the pitch is 5 cm, the cycle number is 10, K = 1.14 (inserted light source magnetic field = 0.2 T), and the total length is 0.8 m. Now, for comparison with the conventional apparatus, the magnetic field of the auxiliary deflection magnet 15 is B = 1.9T, which is the same as the conventional one. In this case, the magnetic field of the main deflection magnet is 4
When T is set, a linear orbit portion for installing the insertion light source between the main deflection magnet and the auxiliary deflection magnet can be created by about 1 m. The circumference of this storage ring is about 17 m, which is about the same as a conventional ring with a peak wavelength of 10 Å. Further, by making the magnetic field of the auxiliary deflection magnet 15 strong or by making the magnetic field have a gradient (weakly converging type), it is possible to configure a smaller system. In this case, the brightness of the radiated light emitted from the insertion light source is about 325 times that of the conventional type, which is equivalent to accumulating a current of about 325 times that of the conventional type. As described above, according to this embodiment, it is possible to generate radiant light that is small and has high brightness.

In the above embodiment, the excitation amount of the main deflection magnet 14 is set to be larger than that of the auxiliary deflection magnet 15, but the radius of curvature or the deflection angle of the main deflection magnet 14 is changed to the auxiliary deflection magnet. The same effect can be obtained by making the radius of curvature of 15 or the deflection angle larger than that of 15 to form a linear track portion between the main deflection magnet 14 and the auxiliary deflection magnet 15 and installing the insertion light source 18 therein. Further, in the above embodiment, the example of the racetrack type storage ring has been described, but the same effect can be obtained with a storage ring having a structure other than this.

Next, a second embodiment of the present invention will be described with reference to FIG. The basic configuration of this embodiment is the same as that shown in FIG.
The main deflecting magnets 14 are replaced by two main deflecting magnets 141 and an insertion light source 18 installed between them. Since the other configurations are the same as those in FIG. 1, description thereof will be omitted here. In the first embodiment shown in FIG. 1, the auxiliary deflection magnets 15,
The electron trajectories of the deflection section formed by the insertion light source 18 and the main deflection magnet 14 are symmetrical with respect to the center line of the main deflection magnet 14. Therefore, even if the main deflection magnet 14 is divided by its center line, it has little effect on the electron trajectories of other parts. A second embodiment shown in FIG. 4 is one in which the main deflection magnet is divided by two along the center line. Since a linear orbital portion is generated between the two divided main deflection magnets 141, the insertion light source 18 can be installed here as well. Therefore, by arranging the two deflecting portions as in this embodiment, six insertion light sources can be installed in the storage ring without changing the circumference of the storage ring so much that the brightness can be reduced by a small storage ring. It is possible to generate radiated light having a high emission and to expand the radiated light extraction region. Thereby, the generated emitted light can be used for a plurality of purposes at the same time.

Next, a third embodiment of the present invention will be described with reference to FIG. In this embodiment, a mirror 51 for condensing the radiation light emitted from the deflection magnet on the outside of the storage ring, and a pattern transfer device for transferring a desired pattern onto the semiconductor substrate using the radiation light condensed by the mirror 51. 52 and 52 are installed. Further, in FIG. 1, the pre-stage accelerator 11 arranged outside the storage ring is arranged inside the storage ring. Since the basic structure of the storage ring of this embodiment is the same as that of FIG. 1, its explanation is omitted here. The brightness of the radiated light other than the peak wavelength decreases as indicated by 31 in FIG. 3, but the radiated light emitted from the main deflection magnet 14 or the auxiliary deflection magnet 15 has a wavelength longer than the peak wavelength. By condensing the light with the mirror 51, this decrease in brightness can be improved. That is, by using the radiated light in the long wavelength range, the radiated light can be reflected and condensed by using the mirror over a wide range of reflection angles, so that the brightness of the radiated light can be increased.
In this way, by guiding the radiated light in the long wavelength region with increased brightness to the pattern transfer device 52, it can be used for reduction exposure processing and the like. Further, in the present embodiment, an example in which the radiation light emitted from the deflection magnet is collected has been shown. However, by collecting the radiation light emitted from the insertion light source, the radiation lights of a plurality of insertion light sources are superposed. It is also possible to use radiant light of higher brightness. Furthermore, in this embodiment, by disposing the pre-accelerator 11 inside the storage ring, the entire device can be made compact and the extraction area of the emitted light can be expanded in a wide range. It can be used for various purposes.

Next, an operating method when a low energy electron beam is incident will be described. In a synchrotron radiation device intended for industrial use, a small installation area is the first requirement. To that end, it is essential to have the function of accelerating the electrons in the storage ring to the desired energy, and the incident energy can be lowered accordingly. Immediately after the incidence, the electron beam has a large betatron oscillation. This amplitude is gradually attenuated by emitting radiation as the electron beam passes through the deflecting magnet. However, when the energy of the electron beam is small, the wavelength of the emitted light is long and the radiation power is also small, so this decay time is very long (several minutes to tens of minutes). Therefore, the incidence cannot be repeated many times. From Equations 1 and 5, the peak wavelength of the emitted light is inversely proportional to the cube of the electron energy and is proportional to the radius of curvature of the deflection magnet. Therefore,
When an electron beam is incident on the storage ring having the configuration shown in FIG. 1, an insertion light source installed between the main deflection magnet and the auxiliary deflection magnet is excited to cause the incident electrons to meander or spiral to accelerate emission of emitted light. Thus, the radiation decay time can be shortened. When the radiation decay time is shortened, the spatial spread (emittance) of the incident electron beam can be reduced, and the loss of the incident electron beam can be suppressed. Furthermore, the electron beam can be injected many times even in a low energy state, and the accumulated current can be increased. Therefore, radiant light with high brightness can be generated.

In the above embodiments, an example using an electron beam has been described, but the same effect can be obtained by using a positron beam.

[0031]

According to the present invention, it is possible to provide a small-sized circular accelerator that can generate radiant light with high brightness, a method of operating the circular accelerator, and a semiconductor exposure apparatus that can use high-radiation radiant light. Further, since the extraction area of the emitted light can be enlarged, the generated emitted light can be used for a plurality of purposes at the same time.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a conventional synchrotron radiation generator.

FIG. 3 is a diagram showing spectral characteristics of radiated light emitted from a deflection magnet and an insertion light source.

FIG. 4 is a schematic diagram showing a second embodiment of the present invention.

FIG. 5 is a schematic diagram showing a third embodiment of the present invention.

[Explanation of symbols]

11 ... Pre-accelerator, 12 ... Electron beam, 13 ... Injector,
14 ... Main deflection magnet, 15 ... Auxiliary deflection magnet, 16 ... Quadrupole magnet, 17 ... High frequency acceleration cavity, 18 ... Insertion light source, 19 ... Radiant light, 31 ... Radiant light spectrum emitted from deflection magnet, 32 ... Wiggler Radiation spectrum emitted from 33, Radiation spectrum emitted from undulator, 51 ... Mirror, 141 ... Main deflection magnet divided into two.

Claims (11)

[Claims] 1. A circular accelerator for accelerating and accumulating an electron beam or a positron beam, characterized in that means for superimposing radiated light is provided on a deflecting portion for deflecting the electron beam or positron beam. 2. A circular accelerator for accelerating and accumulating an electron beam or a positron beam, wherein a deflection part for deflecting the electron beam or the positron beam is provided with a plurality of deflection magnets, and the deflection magnets are adjacent to each other with different excitation amounts. A circular accelerator having a set of magnets, wherein an insertion light source is provided between the deflection magnets. 3. A circular accelerator for accelerating / accumulating an electron beam or a positron beam, wherein a plurality of deflecting magnets are provided in a deflecting part for deflecting the electron beam or the positron beam, and the deflecting magnets are adjacent to each other and have different deflection radii. Have a set of magnets,
A circular accelerator, wherein an insertion light source is provided between the deflection magnets. 4. A circular accelerator for accelerating and accumulating an electron beam or a positron beam, wherein a deflecting unit for deflecting the electron beam or the positron beam is provided with a plurality of deflection magnets, and the deflection magnets have adjacent deflections with different deflection angles. Have a set of magnets,
A circular accelerator, wherein an insertion light source is provided between the deflection magnets. 5. A circular accelerator for accelerating and accumulating an electron beam or a positron beam, wherein a deflecting unit for deflecting the electron beam or the positron beam is provided with a plurality of deflection magnets, and the deflection magnets are adjacent to each other with different excitation amounts. A circular accelerator having a set of magnets and a set of adjacent deflection magnets having the same excitation amount, and an insertion light source provided between the deflection magnets having the same excitation amount. 6. The circular accelerator according to claim 2, wherein a planar or helical undulator or a planar or helical wiggler is used as the insertion light source. Circular accelerator. 7. A circular accelerator for accelerating and accumulating an electron beam or a positron beam, wherein among radiated light emitted from a deflecting section for deflecting the electron beam or positron beam,
A circular accelerator characterized by using radiation in a wavelength range longer than the peak wavelength at which the brightness is maximized. 8. The circular accelerator according to claim 7, further comprising means for reflecting and condensing radiation light having a wavelength longer than the peak wavelength. 9. The circular accelerator according to claim 1, wherein a pre-stage accelerator for the electron beam or positron beam is provided inside a storage ring. 10. The method of operating a circular accelerator according to claim 2, wherein the insertion light source is operated when the electron beam or the positron beam is incident, so that the betatron oscillation of the beam is radiated. A method of operating a circular accelerator, characterized by shortening the decay time. 11. A semiconductor exposure apparatus for exposing a semiconductor by using synchrotron radiation, wherein a plurality of deflecting magnets are provided in a deflecting section for deflecting an electron beam or a positron beam, and the deflecting magnets are adjacent to each other with different excitation amounts. A circular accelerator having a set of deflection magnets and an insertion light source provided between the deflection magnets, a means for reflecting or condensing radiation emitted from the deflecting section, and a means for reflecting or condensing the means. A semiconductor exposure apparatus comprising: a pattern transfer device that transfers a desired pattern onto a semiconductor substrate using synchrotron radiation.